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February 07, 2011 |

In the Magazine

Fuel Filtration

New fuels and new engines demand a new filter regimen

By Tom Jackson

Going green has its drawbacks. When it comes to cleaning up diesel emissions, the price you pay is reduced fuel quality. If you’re not careful, clogged fuel filters and ruined injectors may result.

How particulate and water are removed

Fresh from the refinery, diesel fuel is fairly clean and contaminant free. But the removal of sulfur in ultra low sulfur diesel (ULSD) and the increasing use of biodiesel blends has made today’s fuel less stable and more likely to pick up water and form other contaminants.

The biggest culprits when it comes to fuel contamination have changed as well. “The returned fuel filters we get today are usually plugged with organic matter, rather than inorganic – soft sticky contaminant, rather than hard particles,” says Brian Tucker, engine liquid product manager at Donaldson.

What this means is that you need to fundamentally change how you deal with diesel fuel from your bulk storage tanks to your engine fuel filters. To counteract the threat you first need to be aware of the changes in your fuel and engines.

Biodiesel

“Biodiesel is an industrial solvent,” says Paul Bandoly, manager of technical services/customer training at Wix Filters. This solvent action presents two problems. Initially, when biodiesel is added to your fuel tanks it will dissolve deposits, by-products of oxidation and other contaminants in your system and throw them at the filter.

“If you have dirty dispensing equipment, dirty storage tanks or dirty-on board vehicle systems, you’re going to run through filters like crazy,” Bandoly says.

The second issue with biodiesel is that it loves water. Water breeds microbes and these microbes feed on the fuel and excrete acidic waste products. Dead microbes and waste equal sludge in the tanks. Even when biocides are added to kill microbial growth, that in itself may shorten filter life as the microorganisms are removed by the filter, says Steve Englund, senior product management administrator with Baldwin Filters. Once the system fuel is free from the microbes and/or the residue of biodiesel’s solvent action, filter life should return to normal, Englund says.

Ultra low sulfur diesel

The sulfur levels on diesel fuel, both on and off highway, have been cut more than 95 percent compared to just a few years ago. This naturally occurring sulfur provided lubricity, but today lubricity additives are needed to prevent injection wear, says Brent Birch, engineering lab manager for Luber-Finer/Champion Laboratories.

“In most cases these additives should be added before the fuel is shipped from the distribution terminals to the end users,” Birch says. Soy based bio-fuels are a good lubricity agent. But additives can affect the water separation capabilities of fuel filters and the additives for petroleum diesel and bio-diesel are not necessarily the same, due to differences in fuel chemistry.